One baby 2 sacs

We went today for our first ultrasound. We were not expecting this. They saw 2 sacs and 1 baby with a heartbeat measuring at a little over 6 weeks. Which is what I approximately am. We need to have a repeat ultrasound to verify what is going on with the second sac. It's mostly going to be 1 viable pregnancy :( but it's too early to rule out things. Has anyone else gone through this? How did it turn out?